Method of dehydrating liquids and products obtained thereby



May 15, 1928.

I W. H. DICKERSON METHOD OF DEHYDRATING LIQUIDS AND'PRODUCTS OBTAINED THEREBY Original Fi led Nov. 5, 1922 INVENTOR Patented May 15, 1928.

UNITED STATES,

WALTER E. nroxnnson,

OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO INDUSTRIAL WASTE PRODUCTS CORPORATION, OF DOVER, DELAWARE, A CORPORATION OF DELAWARE.

METHOD OF DEHYDRATING-LIQUIDS AND PRODUCTS OBTAINED THEREBY.

Application filed November 8, 1922,

The invention relates to a method for treating liquids containing low melting point constituents, more especially sugars or like substancesyand, also,

dehydrated and powdered product obtained thereby. The present invention is a continuation in part of my previously filed applications for U. S. Letters Patents, Serial No. 576,384, filed July 20. 1922, and Serial No. 579,297, filed August 2, 1922.

' It has for its object to extract, for example from liquid products containing sugar. such as fruit juices, cane sugar juice, mo- 'lasses, distillery slop liquors, glucose syrup and other liquids containing substances of low melting point characteristics and usually of hygroscopic properties, the sugar or other content in dried powdered form, and anhydrous to a more or less degree. In the production of glucose, for example, the present commercial methods are not conducive to the production of a dried powdered product.

In the well-known process for producing glucose, starch is treated with acid and'the conversion product then evaporated, the concentrated liquid product being of a consistency of 40 to 42 Baum and known as glucose. In addition, there has beenproduced by the conversion of starch thru bydrolyzing to a considerablyfurther degree, a product known as grape sugar, and which solidifies in' the concentrated solution.

The glucose, however, remains as a liquid of viscous consistency which does not admit of abstraction of the contained moisture in the ordinary manner of heating in mass, as the temperature necessary to drive off the remaining moisture would be such as to be injurious to-the glucose and cause decompo- 40 sition of same.

'It is the object of thempresent invention to treat liquids of this character, such as the sugar containing liquids, in manner to avoid this injurious efi'ect. on the constituents; and,

46 furthermore, to preserve, in 'the case of glucose, the degreeof sweetness of, the original syru also, to obtain the same in a dry pow eredcondition;

- To this end, 'the syrup or viscous liquid 0 aforesaid is sprayed or atomized under suitable pressure into heated air or gases at the gripper temperatures to evaporate from the ely divided sprayed material the desired degree of moisture. For example, the

-inch or more, to the novel Serial No. 598,746. Renewed September 26, 1927.

atqpiizing or spraying may be effected at pressures as high as 2000 lbs. per square and the temperature of the heated gaseous medium to which the sprayed material is initially subjected may be as high as 500 F. to 1000 F. However, lower temperatures may be employed, but larger volumes of the drying gaseous medium will be required in such cases.

' Before spraying the material to be dried, it may be desirable to preliminarily concentrate same, as by removing a portion of the water by refrigeration; or, as in the case of glucose; the original solution as it comes from the conversion process and at a specific gravity of from 12 to 18' Baum may,

after filtering, be sprayed directly for comp'lete dehydration to anhydrous powdered product.

In the drying of solutions of materials containing low melting point constituents, as sugars, and more especially such solutions as fruit juices, etc., which containboth low melting point sugars and sugars of highly 'hydroscopic properties, it is necessary not only to reduce the temperatureto which the dry powdered product is exposed to a point sufficiently below the melting point of the particular constituent of low melting point, but also to have the drying gaseous medium of sufliciently low humidity that the finished product will not absorb moisture therefrom when exposed to the low temperature, as provided, for example, by a zone ofcooling gas.

The final temperature to which the material is subjected should thus be belowthe melting point of the material and approximates in the case of glucose generally 180 F., care being taken, also, in the desiccating operation t1 dium does not become saturated to such an extent as to afi'ectthe material which, inthe at the desiccatinggaseous me-' caseof sugars, may be strongly hygroscopic.

in or on the particles and due to the intense evaporation of the moisture content, the material itself not being subjected to the actual high temperatures of -the dryinggas, except the final temperature of evaporation. It has been found that while the individual particles in suspension aresubstantially dry at high temperatures, yet the material in most cases will be in a somewhat melted condition and would adhere to any collecting surface with which it came in contact. Should, therefore, the final temperature of the drying. gas upon completion of evaporation be above the melting point of the material desiccated, the said material must be reduced in temperature by subjecting-the same at once to a suitable lower temperature. This may be effected by chilling the entire body and product in suspension thru. the intro-.

duction of a much cooler gas, or introducing the product into a cooling zone, or by so balancing the amount of evaporation to the amount of heat in the drying gas that the final temperature at the -completion of the drying operation will be at the desired point, for example 180 F., and as is more fully set forth in my aforesaid applications. It may be found necessary, furthermore, where climatic conditions are such that the natural atmospheric air is hot and of high humidity, to first dehydrate-the air prior to its use, as '-well as to dehydrate any further air employed as a cooling med1um.- Ofcourse, in clim'ates'of naturally low humidity, such dehydration will not be necessary. The novel process may be carried out, for exam le, in a vertically disposed drying cham er provided bythe cylindrical casing the to of Whic 1 which is shown in the drawing, said casing being of. appro riate dimensions and into h the material to be dried, and w ich is in a more or less liquid condition, is sprayed. through a spray nozzle 2 of any well-known or special type. Simultaneously therewith, heated gas of the roper'. degree of temperature is mtfoduce thru the top of the casing about the spray nozzle 2, being supplied thru a duct 3 and dis tributing compartment 4. The material thussprayed beco'mesquickly dried into small globular .particles which in their further: travel thru the drying chamber are arranged to. pass througha cooling zone or zones to -chill the same to the desired final temperature, preliminary to withdrawal from said casing. These zones may conveniently be provided thru the medium of one or more sets of annular openings 5 and 6 respectively disposed in thewall of the casing one at its lower portion and thru which a gaseous cooling medium may be directed from suitable supply ducts 7 and 8, respectively.

The. product in its. final; condition. will, therefore, have been chilled, immediately upon completion of the, evaporation, to a dinary glucose from treatment of starch with acid, results In impairment of the sweetnessof the product in its natural .state.' This is probably as a result ofthe boiling down operation in vacuum pans and no doubt due to the effect of the long exposure of the syrup to the heat required in the evaporation process.

I claim:-

.. 1. The. method of producing anhydrous powdered glucose, which cons1stsin subjectinga; water solution of glucose in a state of, minute subdivision to a dehydrating gaseous medium, and at the completion of the dryingoperation subjecting the desiccated .product immediately and while in suspension to atemperature below the melting point of the powderedproduct.

2. The method of producing anhydrous powdered glucose, which consists in subjectlng awater'solution of glucose in a state of minute sub ivi sion to a dehydrating gaseous medium at an initial temperature of from 500 vF. to'1000 F., and at the completion of the drying operation subjectin the desiccated product immediately and w He in suspension to the action of a gas at a tempera-- ture below the terminal temperature of the gaseous medium and .the melting point of tli e' 'powdered ,product.

3. The. method of producing anhydro powdered glucose, which consists in subject-- i sing a water solution of glucose in a state of ehydrating gaseous 7 medium at an initial'temperature of from r 500 F. to1000 F-.-, and at the completion of the drying operation'subjecting the desic-' minute subdivision to a cated product immediately and while in suspension to a temperature'below 180 F.'

Signed at New York, in the county of New-York and.State of New York, this 31st f day of October, A.' D. 1922.

WALTER DIGKERSON. 

